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Method for the formation of a sacrificial oxide-on-copper seed surface

IP.com Disclosure Number: IPCOM000007550D
Publication Date: 2002-Apr-04
Document File: 2 page(s) / 21K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for the formation of a sacrificial oxide-on-copper seed surface. Benefits include improved reliability.

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Method for the formation of a sacrificial oxide-on-copper seed surface

Disclosed is a method for the formation of a sacrificial oxide-on-copper seed surface. Benefits include improved reliability.

Background

              The conventional method for forming copper interconnects is comprised of the following steps:

1.      Pattern a trench in a dielectric surface.

2.      Deposit a barrier/seed layer on the surface of the wafer.

3.      Use electroplating to fill the trenches and cover the surface of the wafer with a thick layer of copper.

4.      Perform chemical mechanical planarization (CMP) to remove copper outside of the trenches.

              A key problem is that contamination of the surface of the seed inhibits subsequent trench fill by electroplating which leads to defects in the copper.

Description

              The disclosed method includes the addition of a small concentration of oxygen to the gas flowing over the wafer inside the barrier/seed deposition tool after the copper seed is deposited (see Figure 1). The addition of oxygen forms copper oxide on the surface of the copper seed.

              The copper oxide is quickly removed during the initial portion of the electroplating process (see Figure 2). Any contamination on the surface of the copper seed is dissolved away along with the copper oxide. Electroplating can occur on a clean copper surface to avoid defects (see Figure 3). CMP is performed on the wafer (see Figure 4).

Advantages

              Any contamination on the top surface of the seed layer is removed as the copper oxide is dissolved...